I would pay for the app if there was a paywall.
I’m donating to the things I use: Debian, Gnome, FSF, Wikipedia, Adblock Plus and even Mozilla, though lately I’m tempted to rethink this one.
On the other hand it is very hard to sell any app to me, since I do not use computers to do anything real, and my first line of action is to look for a freedom software that does what I need.